10.5.1 Patterns of Reactivity IGCSE Chemistry 10.5.1 Patterns of Reactivity

Comparing orders of reactivity When the orders of reactivity of metals with water, oxygen and air are compared, there is a pattern of results. with water potassium sodium lithium magnesium copper silver gold with oxygen magnesium iron copper with acid calcium magnesium aluminium zinc iron lead copper Combining the information from all the reactions of metals with water, oxygen and air gives an overall order of reactivity called the reactivity series.

increasing reactivity The reactivity series The reactivity series is the list of metals placed in order of their reactivity. One way to remember this order is to learn this silly sentence: potassium sodium calcium magnesium aluminium zinc iron lead copper silver gold Please send Charlie’s monkeys and zebras in lead cages securely guarded! increasing reactivity

What is the order of metals?

Using the reactivity series The reactivity series can be used to make predictions about the reactions of metals. Predictions can be made about simple reactions of metals with oxygen, water and acids. Predictions can also be made about more complex reactions where one metal is competing with another. potassium sodium calcium magnesium aluminium zinc iron lead copper silver gold increasing reactivity

Simple reactions – predictions Use the reactivity series to predict if a reaction will take place and how intense the reaction will be. Metal React with Prediction gold acid calcium water sodium oxygen silver zinc potassium sodium calcium magnesium aluminium zinc iron lead copper silver gold no reaction fizzing burns vigorously very slow reaction burns moderately

When does displacement happen? The reactivity series can be used to predict if a metal will react with a metal compound (e.g. chloride, nitrate or sulfate). If the metal is more reactive than the metal in the compound, it competes with the less reactive metal.  + less reactive metal compound more reactive metal + less reactive metal more reactive metal compound The more reactive metal pushes out, or displaces, the less reactive metal from its compound. If the metal is less reactive than the metal in the compound, it will not compete and so there is no reaction. + no reaction  more reactive metal compound less reactive metal

Displacement reactions – examples The reactivity series can be used to predict if a metal will react with a metal compound. Will magnesium react with copper chloride?  copper chloride + magnesium copper + magnesium chloride Magnesium is a more reactive metal than copper, so magnesium displaces the copper from its compound. Will silver react with magnesium chloride?  magnesium chloride + silver no reaction Silver is a less reactive metal than magnesium, so silver does not displace the magnesium from its compound.

Displacement reactions – observation This photograph shows what happens when magnesium reacts with copper sulfate. Why does the blue colour of the coppers sulfate solution gradually disappear during this reaction? before after copper + magnesium sulfate  copper sulfate magnesium Magnesium is a more reactive metal than copper and so the magnesium displaces the copper from the copper sulfate solution. This is why the blue colour disappears.

Displacement of sulfates – predictions Use the reactivity series to predict if there is a reaction when these metals are added to different metal sulfate solutions. magnesium sulfate zinc sulfate iron copper sulfate magnesium copper metal sulfate solution metal              = displacement reaction = no reaction 

Displacement of sulfates – magnesium Does magnesium react with and displace these metal sulfates and if so what products are formed?  copper sulfate + magnesium magnesium sulfate + copper  Mg + CuSO4  MgSO4 Cu  zinc sulfate + magnesium magnesium sulfate + zinc  Mg + ZnSO4  MgSO4 Zn  iron sulfate + magnesium magnesium sulfate + iron  Mg + FeSO4  MgSO4 Fe

Displacement of sulfates – zinc Does zinc react with and displace these metal sulfates and if so what products are formed?   magnesium sulfate + zinc no reaction  iron sulfate + zinc zinc sulfate + iron  Zn + FeSO4  ZnSO4 Fe  copper sulfate + zinc zinc sulfate + copper  Zn + CuSO4  ZnSO4 Cu

Displacement of sulfates – iron Does iron react with and displace these metal sulfates and if so what products are formed?   magnesium sulfate + iron no reaction   zinc sulfate + iron no reaction  copper sulfate + iron iron sulfate + copper  Fe + CuSO4  FeSO4 Cu

Displacement of sulfates – copper Does copper react with and displace these metal sulfates and if so what products are formed?   magnesium sulfate + copper no reaction   zinc sulfate + copper no reaction   copper sulfate + copper no reaction

Displacement of oxides Displacement reactions can also occur between a metal and a metal compound that is a solid.  iron oxide + aluminium iron + aluminium oxide The more reactive aluminium wins the oxygen from the less reactive iron. The reaction gets so hot that the iron melts! This is the Thermit reaction and is used to weld railway lines.

Displacement of oxides – predictions Use the reactivity series to predict if there is a reaction when each mixture of a metal and a metal oxide is heated. zinc oxide iron copper oxide copper metal oxide metal        = displacement reaction = no reaction 

Displacement of oxides – zinc Does zinc react with and displace these metal oxides and if so what products are formed?  copper oxide + zinc zinc oxide + copper  Zn + CuO  ZnO Cu  iron oxide + zinc zinc oxide + iron  3Zn + 2Fe2O3  3ZnO 2Fe Zinc is the more reactive than copper and iron.

Displacement of oxides – iron Does iron react with and displace these metal oxides and if so what products are formed?   zinc oxide + iron no reaction  copper oxide + iron iron oxide + copper  2Fe + 3CuO  Fe2O3 3Cu Iron is less reactive than zinc but more reactive than copper.

Displacement of oxides – copper Does copper react with and displace these metal oxides and if so what products are formed?   zinc oxide + copper no reaction   iron oxide + copper no reaction Copper is less reactive than zinc and iron and will not displace either of these metals.

Displacement reactions – activity Use the reactivity series to predict if each mixture will react. Reactants Reaction? iron oxide magnesium potassium sodium calcium magnesium aluminium zinc iron lead copper silver gold  copper sulfate zinc  potassium hydrochloric acid   gold iron chloride  calcium sodium chloride calcium oxygen 

Displacement reactions – activity Use the reactivity series to predict if each mixture will react and complete the word equation.  aluminium oxide + magnesium magnesium oxide + aluminium  iron chloride + magnesium magnesium chloride + iron  zinc oxide + silver no reaction  gold nitrate + copper copper nitrate + gold

reactive – A substance that reacts quickly or easily. Glossary displaced metal – The metal that is pushed out of a compound by a more reactive metal. displacement – A reaction in which a more reactive metal replaces a less reactive metal in a compound. reactive – A substance that reacts quickly or easily. reactivity – How quickly or easily a substance will react. reactivity series – The list of metals placed in order of their reactivity starting with the most reactive. tarnished – A metal that has become dull after reacting with water and oxygen in the air. Thermite reaction – The displacement reaction between aluminium and iron oxide that is used to weld railway lines. unreactive – A substance that reacts very slowly or does not react at all.